source: sasview/DataLoader/smearing_2d.py @ 35b556d

"""
This software was developed by the University of Tennessee as part of the
Distributed Data Analysis of Neutron Scattering Experiments (DANSE)
project funded by the US National Science Foundation. 

See the license text in license.txt

copyright 2009, University of Tennessee
"""
## TODO: Need test,and check Gaussian averaging
import numpy, math,time
## Singular point
SIGMA_ZERO = 1.0e-010
## Limit of how many sigmas to be covered for the Gaussian smearing
# default: 2.5 to cover 98.7% of Gaussian
LIMIT = 2.5
## Defaults
R_BIN = {'Xhigh':10.0, 'High':5.0,'Med':5.0,'Low':3.0}
PHI_BIN ={'Xhigh':20.0,'High':12.0,'Med':6.0,'Low':4.0}   

class Smearer2D:
    """
        Gaussian Q smearing class for SANS 2d data
    """
     
    def __init__(self, data=None,model=None,index=None,limit=LIMIT,accuracy='Low'):
        """
            Assumption: equally spaced bins in dq_r, dq_phi space.
            
            @param data: 2d data used to set the smearing parameters
            @param model: model function
            @param index: 1d array with len(data) to define the range of the calculation: elements are given as True or False
            @param nr: number of bins in dq_r-axis
            @param nphi: number of bins in dq_phi-axis
        """
        ## data
        self.data = data
        ## model
        self.model = model
        ## Accuracy: Higher stands for more sampling points in both directions of r and phi.
        self.accuracy = accuracy
        ## number of bins in r axis for over-sampling 
        self.nr = R_BIN
        ## number of bins in phi axis for over-sampling 
        self.nphi = PHI_BIN
        ## maximum nsigmas
        self.limit = limit
        self.index = index
        self.smearer = True
        
        
    def get_data(self):   
        """
            get qx_data, qy_data, dqx_data,dqy_data,and calculate phi_data=arctan(qx_data/qy_data)
        """
        if self.data == None or self.data.__class__.__name__ == 'Data1D':
            return None
        if self.data.dqx_data == None or self.data.dqy_data == None:
            return None
        self.qx_data = self.data.qx_data[self.index]
        self.qy_data = self.data.qy_data[self.index]
        self.dqx_data = self.data.dqx_data[self.index]
        self.dqy_data = self.data.dqy_data[self.index]
        self.phi_data = numpy.arctan(self.qx_data/self.qy_data)
        ## Remove singular points if exists
        self.dqx_data[self.dqx_data<SIGMA_ZERO]=SIGMA_ZERO
        self.dqy_data[self.dqy_data<SIGMA_ZERO]=SIGMA_ZERO
        return True
    
    def set_accuracy(self,accuracy='Low'):   
        """
            Set accuracy:  string
        """
        self.accuracy = accuracy

    def set_smearer(self,smearer = True):
        """
            Set whether or not smearer will be used
        """
        self.smearer = smearer
        
    def set_data(self,data=None):   
        """
            Set data:  1d arrays
        """
        self.data = data
  
            
    def set_model(self,model=None):   
        """
            Set model
        """
        self.model = model  
           
    def set_index(self,index=None):   
        """
            Set index: 1d arrays
        """

        self.index = index       
    
    def get_value(self):
        """
            Over sampling of r_nbins times phi_nbins, calculate Gaussian weights, then find smeared intensity
            # For the default values, this is equivalent (but speed optimized by a factor of ten)to the following:
            =====================================================================================
            ## Remove the singular points if exists
            self.dqx_data[self.dqx_data==0]=SIGMA_ZERO
            self.dqy_data[self.dqy_data==0]=SIGMA_ZERO
            for phi in range(0,4):
                for r in range(0,5):
                    n = (phi)*5+(r)
                    r = r+0.25
                    dphi = phi*2.0*math.pi/4.0 + numpy.arctan(self.qy_data[index_model]/self.dqy_data[index_model]/self.qx_data[index_model]*/self.dqx_data[index_model])
                    dq = r*numpy.sqrt( self.dqx_data[index_model]*self.dqx_data[index_model] \
                        + self.dqy_data[index_model]*self.dqy_data[index_model] )
                    #integrant of math.exp(-0.5*r*r) r dr at each bins : The integration may not need.
                    weight_res[n] = math.exp(-0.5*((r-0.25)*(r-0.25)))-math.exp(-0.5*((r-0.25)*(r-0.25)))
                    #if phi !=0 and r != 0:
                    qx_res=numpy.append(qx_res,self.qx_data[index_model]+ dq*math.cos(dphi))
                    qy_res=numpy.append(qy_res,self.qy_data[index_model]+ dq*math.sin(dphi))
            ## Then compute I(qx_res,qy_res) and do weighted averaging. 
            =====================================================================================
        """
        valid = self.get_data()
        if valid == None:
            return valid
        if self.smearer == False:
            return self.model.evalDistribution([self.qx_data,self.qy_data]) 
        st = time.time()
        nr = self.nr[self.accuracy]
        nphi = self.nphi[self.accuracy]

        # data length in the range of self.index
        len_data = len(self.qx_data)
        len_datay = len(self.qy_data)

        # Number of bins in the dqr direction (polar coordinate of dqx and dqy)
        bin_size = self.limit/nr
        # Total number of bins = # of bins in dq_r-direction times # of bins in dq_phi-direction
        n_bins = nr * nphi
        # Mean values of dqr at each bins ,starting from the half of bin size
        r = bin_size/2.0+numpy.arange(nr)*bin_size
        # mean values of qphi at each bines
        phi = numpy.arange(nphi)
        dphi = phi*2.0*math.pi/nphi
        dphi = dphi.repeat(nr)
        ## Transform to polar coordinate, and set dphi at each data points ; 1d array
        dphi = dphi.repeat(len_data)+numpy.arctan(self.qy_data*self.dqx_data/self.qx_data/self.dqy_data).repeat(n_bins).reshape(len_data,n_bins).transpose().flatten()
        ## Find Gaussian weight for each dq bins: The weight depends only on r-direction (The integration may not need)
        weight_res = numpy.exp(-0.5*((r-bin_size/2.0)*(r-bin_size/2.0)))-numpy.exp(-0.5*((r+bin_size/2.0)*(r+bin_size/2.0)))
        weight_res = weight_res.repeat(nphi).reshape(nr,nphi).transpose().flatten()
        
        ## Set dr for all dq bins for averaging
        dr = r.repeat(nphi).reshape(nr,nphi).transpose().flatten()
        ## Set dqr for all data points
        dqx = numpy.outer(dr,self.dqx_data).flatten()
        dqy = numpy.outer(dr,self.dqy_data).flatten()
        qx = self.qx_data.repeat(n_bins).reshape(len_data,n_bins).transpose().flatten()
        qy = self.qy_data.repeat(n_bins).reshape(len_data,n_bins).transpose().flatten()

        
        ## Over-sampled qx_data and qy_data.
        qx_res = qx+ dqx*numpy.cos(dphi)
        qy_res = qy+ dqy*numpy.sin(dphi)
        
        ## Evaluate all points
        val = self.model.evalDistribution([qx_res,qy_res]) 

        ## Reshape into 2d array to use numpy weighted averaging
        value_res= val.reshape(n_bins,len(self.qx_data))

        ## Averaging with Gaussian weighting: normalization included.
        value =numpy.average(value_res,axis=0,weights=weight_res)

        ## Return the smeared values in the range of self.index
        return value
    
    
if __name__ == '__main__':
    ## Test
    x = 0.001*numpy.arange(1,11)
    dx = numpy.ones(len(x))*0.001
    y = 0.001*numpy.arange(1,11)
    dy = numpy.ones(len(x))*0.001
    z = numpy.ones(10)
    dz = numpy.sqrt(z)
    
    from DataLoader import Data2D
    #for i in range(10): print i, 0.001 + i*0.008/9.0 
    #for i in range(100): print i, int(math.floor( (i/ (100/9.0)) )) 
    out = Data2D()
    out.data = z
    out.qx_data = x
    out.qy_data = y
    out.dqx_data = dx
    out.dqy_data = dy
    index = numpy.ones(len(x), dtype = bool)
    out.mask = index
    from sans.models.Constant import Constant
    model = Constant()

    value = Smearer2D(out,model,index).get_value()
    ## All data are ones, so the smeared should also be ones.
    print "Data length =",len(value), ", Data=",value